H and D ∕ H analysis in olivine and wadsleyite with a multi-analytical approach combining Raman spectroscopy and ion and nuclear probes
<p>The most abundant mineral in the upper mantle, olivine, is described as nominally anhydrous, while its high-pressure polymorph, wadsleyite, can contain up to 3 % H<span class="inline-formula"><sub>2</sub></span>O by weight. Here we focus on the quantificati...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-05-01
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| Series: | European Journal of Mineralogy |
| Online Access: | https://ejm.copernicus.org/articles/37/305/2025/ejm-37-305-2025.pdf |
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| Summary: | <p>The most abundant mineral in the upper mantle, olivine, is described as nominally anhydrous, while its high-pressure polymorph, wadsleyite, can contain up to 3 % H<span class="inline-formula"><sub>2</sub></span>O by weight. Here we focus on the quantification of total H<span class="inline-formula"><sub>2</sub></span>O content, dissolved as hydroxyl (OH), as well as hydrogen isotopic composition, i.e. <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">D</mi><mo>/</mo><mi mathvariant="normal">H</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="930dd7e3de32880de8db3a2da0740eed"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-37-305-2025-ie00004.svg" width="24pt" height="14pt" src="ejm-37-305-2025-ie00004.png"/></svg:svg></span></span> ratios, in olivine and wadsleyite using a multi-instrument approach. Our aim is to establish a calibration procedure that allows accurate quantification of the hydrogen content and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">D</mi><mo>/</mo><mi mathvariant="normal">H</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="e4022fe1fd207c62e15fbadd87aa382d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-37-305-2025-ie00005.svg" width="24pt" height="14pt" src="ejm-37-305-2025-ie00005.png"/></svg:svg></span></span> ratios of D-doped experimental samples using Raman spectroscopy, as confirmed by secondary-ion mass spectrometry (SIMS). Olivine and wadsleyite samples were synthesized under hydrothermal conditions at high pressure and doped with deuterium. Olivine and wadsleyite reference materials that were previously characterized by both Fourier-transform infrared (FTIR) spectroscopy and elastic recoil detection analysis (ERDA) were used to calibrate the measurement of water concentrations in the samples using both Raman spectroscopy and SIMS. D-doped olivine reference materials were characterized by ERDA (which is a point beam technique with the advantage of being an absolute quantification method) to find their <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">D</mi><mo>/</mo><mi mathvariant="normal">H</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="1a8248039cc78c598c0e30bf487dec86"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-37-305-2025-ie00006.svg" width="24pt" height="14pt" src="ejm-37-305-2025-ie00006.png"/></svg:svg></span></span> ratio and used to determine the instrument mass fractionation of H isotopes with the ion probe. Then we compared the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">D</mi><mo>/</mo><mi mathvariant="normal">H</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c78995d3f67856633c35697a267d9112"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-37-305-2025-ie00007.svg" width="24pt" height="14pt" src="ejm-37-305-2025-ie00007.png"/></svg:svg></span></span> ratios determined by SIMS to the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">OD</mi><mo>/</mo><mi mathvariant="normal">OH</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="2cc1e29e7cbb5e6250616346ce803788"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-37-305-2025-ie00008.svg" width="41pt" height="14pt" src="ejm-37-305-2025-ie00008.png"/></svg:svg></span></span> intensity ratio determined by Raman spectroscopy for three wadsleyite samples, finding a conversion factor of 0.85 (error of <span class="inline-formula">∼2</span> %). After correction of the instrument response, we find that the Raman scattering cross-section (<span class="inline-formula"><i>K</i></span>) of OH is slightly lower than that of OD; still <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi>K</mi><mi mathvariant="normal">OH</mi></msub><mo>/</mo><msub><mi>K</mi><mi mathvariant="normal">OD</mi></msub><mo>=</mo><mn mathvariant="normal">0.95</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="81pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c3bf3845ff844d5d2ce2456a7fe38c05"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-37-305-2025-ie00009.svg" width="81pt" height="14pt" src="ejm-37-305-2025-ie00009.png"/></svg:svg></span></span> is in agreement with previous studies. <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">D</mi><mo>/</mo><mi mathvariant="normal">H</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="1da8140e20db6bd42f7b603d40e61948"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-37-305-2025-ie00010.svg" width="24pt" height="14pt" src="ejm-37-305-2025-ie00010.png"/></svg:svg></span></span> ratios in doped samples can therefore be determined using Raman spectroscopy, which is a more accessible technique than SIMS, with a detection limit of <span class="inline-formula">90±10</span> ppm wt for both D<span class="inline-formula"><sub>2</sub></span>O and H<span class="inline-formula"><sub>2</sub></span>O.</p> |
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| ISSN: | 0935-1221 1617-4011 |